tRNAdb 2009, to be updated regularly, provides various services including graphical representations of tRNA secondary structures, a customizable output of aligned or un-aligned sequences with a variety of individual and combinable search criteria, the construction of consensus sequences for any selected set of tRNAs, as well as the illustration of consensus and derived typical cloverleaf structures with features of conservation for any selected set of tRNAs. Furthermore, the implementation of the NCBI taxonomy tree facilitates phylogeny-related queries. The new tRNA database can be accessed at http://trnadb.bioinf.uni-leipzig.de.